1. Field of the Invention
The present invention generally relates to a method for reforming ground-condition by using an instantaneous hardening type hardening material or a combination of a slow hardening type hardening material and a high pressure air to reform soft ground conditions and harden foundations of building sites. More particularly, two components of the instantaneous hardening type hardening material are injected into the ground through a two fluid mixing nozzle at the same occasion.
Further, the present invention relates to a device for reforming ground-condition by using the two fluid mixing nozzle.
2. Description of the Prior Art
Conventionally, various ground reforming methods using a hardening material jet have been provided. In these methods, high pressure and high speed jet injection has been applied to only a slow hardening type hardening material, on the other hand an instantaneous hardening type hardening material has been injected under a low pressure approaching ambient pressure. The high pressure injection has been conducted at highest 200 kg f/cm.sup.2, and no injection device adapted for higher injection pressures has yet been proposed.
The instantaneous hardening type hardening material can not be used for such high pressure injection type ground reforming method because the instantaneous hardening type hardening material is composed of two separated liquids which should be mixed after injection. If these two liquids are mixed prior to injection, the hardening material will be wholly or partially hardened in an injection pump or pipe. Therefore the high pressure injection method has employed the slow hardening type hardening material which requires a long period to achieve hardening. However, the slow hardening type hardening material will sometimes cause problems owing to its slow hardening speed. For example, if the injection amount is increased, the slow hardening type hardening material will flow backwards to leak out of the injection pipe or the like. Special injection angles such as horizontal injection or upward injection, will remarkably cause such problems and thus can not employ the high pressure injection method.
In the high pressure injection method, reaction force will be generated at the injection nozzle as the injection pressure is increased, and the reaction force will be applied to an injection rod. Revolving motion of the injection rod will be affected by the reaction force and as a result the injection rod will result in serious trouble.